#include <iostream>
using namespace std;
int main()
{
	int nums=703;
	for(char x1='A';x1<='Z';++x1)
	{
		for(char x2='A';x2<='Z';++x2)
		{
			for(char x3='A';x3<='Z';++x3)
			{
				nums++;
				if(nums==2019)
				{
					cout<<x1<<x2<<x3;
				}
			}
		}
	}
  return 0;
}
